1. Field of the Invention
The present invention relates to a producing method of a light emitting element transfer sheet, a producing method of a light emitting device, a light emitting element transfer sheet, and a light emitting device, to be specific, to a producing method of a light emitting element transfer sheet and a light emitting element transfer sheet obtained by the method, and a producing method of a light emitting device and a light emitting device obtained by the method.
2. Description of Related Art
In recent years, as a light emitting device that is capable of emitting high-energy light, a white light emitting device has been known. In the white light emitting device, for example, a diode board, an LED (light emitting diode) laminated thereon, emitting blue light, a phosphor layer that can convert the blue light into yellow light and covers the LED, and an encapsulating layer that encapsulates the LED are provided. The white light emitting device emits high-energy white light by color mixing of the blue light emitted from the LED, which is encapsulated by the encapsulating layer and to which electric power is supplied from the diode board, transmitting through the encapsulating layer and the phosphor layer, and the yellow light that is converted in wavelength from a part of the blue light in the phosphor layer.
As a method for producing the white light emitting device, for example, the following method has been proposed (ref: for example, Japanese Unexamined Patent Publication No. 2005-191420).
The proposed method is as follows. That is, a base, which has a board portion and a white reflecting frame portion protruding from the circumference portion thereof toward the upper side, is first formed. Next, a semiconductor light emitting element is subjected to a wire bonding in a bottom portion of a concave portion, which is formed at the center of the board portion by the reflecting frame portion, so as to be spaced apart from the inner side of the reflecting frame portion.
Next, a mixture of a phosphor and an epoxy resin in a liquid state is filled in the concave portion by application, subsequently the phosphor is spontaneously precipitated in the bottom portion of the concave portion, and then the epoxy resin is heat cured.
In the white light emitting device obtained by the method proposed in Japanese Unexamined Patent Publication No. 2005-191420, the phosphor layer (a wavelength conversion layer) that contains the phosphor formed by a precipitation at high concentrations is defined in a region at the upper side of the semiconductor light emitting element and an encapsulating portion that contains the epoxy resin at high concentrations is defined in a region at the upper side of the phosphor layer.
In the white light emitting device, the semiconductor light emitting element radially emits the blue light. Of the emitted blue light, a part thereof emitted from the semiconductor light emitting element toward the upper side is converted into the yellow light in the phosphor layer and the remaining light transmits through the phosphor layer. The blue light emitted from the semiconductor light emitting element toward the side is reflected at the reflecting frame portion and then toward the upper side. The white light emitting device in Japanese Unexamined Patent Publication No. 2005-191420 emits the white light by color mixing of the blue light and the yellow light.